The Prenatal PCB Exposure and Neurodevelopmental Outcomes in Adolescence and Adulthood study will examine the relationship between prenatal exposure to polychlorinated biphenyls (PCBs) and cognitive, behavioral, neurologic, and psychiatric outcomes in adolescence and adulthood. The study will be based in a sub-cohort consisting of 162 African-American subjects whose mothers were enrolled during pregnancy in 1962 and 1963 at Columbia Presbyterian Medical Center (CPMC) in the Collaborative Perinatal Project (CPP) and who participated in a follow-up study when they were 16 to 18 years of age. The strengths of the study include stored prenatal maternal serum to assess PCB exposure with state-of-the-art laboratory methods, a study population already examined for relevant outcomes as adolescents and accessible as adults, a rich array of data on relevant covariates, and extension of PCB developmental toxicity research into a high-risk, socially disadvantaged urban population. The study will be carried out in two phases, corresponding to the two main aims described below. The study aims first, to evaluate the relation of prenatal PCB exposure to neurodevelopmental outcomes in adolescence. Exposure will be assessed through PCB assays to be performed on stored prenatal sera. Outcome data will be derived from assessments of intelligence, memory, spatial reasoning, reading comprehension, neurological soft signs, classroom behavior, and the presence of conduct and affective disorders. These assessments were performed during a previous study when the subjects were between 16 and 18 years of age. Information potential confounding social and biomedical factors obtained during the prenatal, perinatal, childhood, and adolescent periods will also be used. The second specific aim is to evaluate the relation of prenatal PCB exposure to neurodevelopmental outcomes at age 39 and over the life course through that age in the same sub-cohort studied in the phase 1 study. Exposure assessments will employ the same PCB assays performed on stored prenatal sera during phase 1. Outcomes will be measured by tracing and recruiting subjects to undergo an examination battery comprised of a) repeating the measures of intelligence, memory, and spatial reasoning used in the phase 1 study and b) additional refined neuropsychologic, neurologic, behavioral, and psychiatric assessments determined from the phase 1 findings. This project is closely integrated with the Exposure Assessment and Biometry Cores of the proposed Center, which will support PCB analyses and biostatistical consultation for the project. This project also complements Project 2 of the proposed Center, which will assess developmental neurotoxicity of prenatal PCB exposure in infants, and the approach to exposure assessment will be closely coordinated between the two projects.